1. Field of the Invention
This invention relates to a novel butene-1 copolymer composition More particularly, it relates to a butene-1 copolymer composition which is superior in flame retardancy and emits no toxic gas even if it burns and superior in mechanical strength and is suitable as materials for wire coating.
2. Description of the Related Art
Crystalline butene-1 copolymers have been positively developed in their uses because of their superior creep characteristics, high strength against distortion and high heat resistance. However, the butene-1 copolymers also have the defect of easy flammability like other polyolefins.
Hitherto, flame-retardation of thermoplastic resins has been made by adding a halogen compound as a flame-retardant to thermoplastic resins. However, such thermoplastic resins containing a halogen compound emit toxic gas when burning.
In order to solve this problem, adding magnesium hydroxide and carbon powder to thermoplastic resins in place of the halogen compound has been proposed. (See Japanese Patent Kokoku No. 57-10898). This publication discloses polybutene-1 as an example of thermoplastic resins.
However, when said materials are applied to ordinary polybutene-1 such as butene-1 homopolymer, flame-retardancy can be improved, but reduction in mechanical characteristics is recognized and thus this method is not satifactory.
Furthermore, a composition of polybutene-1 in which magnesium hydroxide and a modified polyolefin are incorporated has been proposed. (See Japanese Patent Kokai No. 59-210963). This composition also suffers from the problem of insufficient mechanical properties.